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Thu, 25 Feb 2021 18:27:35 +0000 (UTC) Received: from [10.36.114.58] (ovpn-114-58.ams2.redhat.com [10.36.114.58]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0475A1346D; Thu, 25 Feb 2021 18:27:33 +0000 (UTC) Subject: Re: [PATCH v2 5/7] mm,memory_hotplug: Enforce pageblock alignment when memmap_on_memory To: Oscar Salvador , Andrew Morton Cc: Michal Hocko , VlastimilBabkavbabka@suse.cz, pasha.tatashin@soleen.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Anshuman Khandual References: <20210209133854.17399-1-osalvador@suse.de> <20210209133854.17399-6-osalvador@suse.de> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <9fcd9246-8e27-2991-a32f-539d9a430514@redhat.com> Date: Thu, 25 Feb 2021 19:27:33 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: <20210209133854.17399-6-osalvador@suse.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Stat-Signature: xy3zub61is7yr45kcxwf77ugc4xutdta X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: F28BC20003AE Received-SPF: none (redhat.com>: No applicable sender policy available) receiver=imf11; identity=mailfrom; envelope-from=""; helo=us-smtp-delivery-124.mimecast.com; client-ip=216.205.24.124 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1614277659-779126 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 09.02.21 14:38, Oscar Salvador wrote: > Many places expects us to pass a pageblock aligned range. > E.g: memmap_init_zone() needs a pageblock aligned range in order > to set the proper migrate type for it. > online_pages() needs to operate on a pageblock aligned range for > isolation purposes. > > Make sure we disable the feature in case we cannot guarantee the > right alignment. > > Signed-off-by: Oscar Salvador > --- > mm/memory_hotplug.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index d3fb036d33fd..1a4d5dd1a2c8 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -56,12 +56,16 @@ static int memmap_on_memory_show(char *buffer, const struct kernel_param *kp) > static __meminit int memmap_on_memory_store(const char *val, > const struct kernel_param *kp) > { > + unsigned long pageblock_size = PFN_PHYS(pageblock_nr_pages); > + > /* > * Fail silently in case we cannot enable it due to system constraints. > * User can always check whether it is enabled or not via /sys/module. > */ > if (!IS_ENABLED(CONFIG_ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE) || > - (PMD_SIZE % sizeof(struct page))) > + (PMD_SIZE % sizeof(struct page)) || > + !(MIN_MEMORY_BLOCK_SIZE - PMD_SIZE) || > + !(MIN_MEMORY_BLOCK_SIZE - PMD_SIZE) % pageblock_size) > return 0; > > return param_set_bool(val, kp); > Dito, rather squash in #1 and add a comment explaining what's happening there. -- Thanks, David / dhildenb